HPC are less technical and thus for athletes with little time to develop Oly technique (or who have been taught poor technique from high school or whatever).... they can derive the most benefit from an explosive lift with the least amount of time.

The more weight you can use the more powerful... and that's definitely the full lifts.

Wouldn't that make the C+J more powerful than the snatch? Same range of motion, but a lot more weight in the C+J than the snatch.

Power = work/time. (I just stated the work component of power above)

Snatch is a faster lift (to overhead) which is why it requires more power to do it at the expense of a bit of work though (and more technique as well).

If you're talking about racked clean vs. snatch they may be more similar because they take more or less probably a similar amount of time... the only difference is weight and distance of the bar traveled.

Clean a bit ahead of snatch at lower weight class, snatch higher than clean at heavier weight classes. For all intents and purposes fairly equivalent though as the same muscles are used to get the weight up in both.